JPS5928230B2 - Photocurable insulation varnish - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photocurable insulating varnish characterized by containing an allyl group as a photopolymerizable crosslinking group.

Furthermore, the present invention provides a photocurable insulating varnish that has a long pot life, good thermal stability, and exhibits a high level of insulating varnish performance. In recent years, issues of resource conservation, energy conservation, and pollution-free production have become increasingly important, and insulating materials and processing processes are also moving in a direction that takes these social demands into account.

For example, the widespread use of solvent-free insulating varnishes, the introduction of powder insulation treatment methods, and electrodeposition insulation treatment methods using water-soluble varnishes or water-dispersible varnishes are becoming widespread. However, all of these material groups and processing methods ultimately use heating to harden the insulating varnish, and are used to insulate areas where heat treatment is difficult, such as insulation after attaching low-heat electronic components or coatings. In cases where the heat capacity of the processed material is large and the efficiency of thermal energy use is low,
There is an urgent need for a rational, high-efficiency varnish curing method to be developed. The present invention was carried out by focusing on a photocuring method as a method for curing insulating varnish without using heating means.

Although active research is currently being conducted in the field of the coating industry on photocuring methods for paints, these photocurable paints intended for general coating cannot be used as they are as electrical insulating varnishes. However, electrical equipment is used in harsh external environments, and typical external stimulation factors are thermal, electrical, or mechanical, and these factors are usually introduced in combination. There are many things. Therefore, insulating varnishes are required to have the above-mentioned material properties at a high level, and also have excellent water resistance and chemical resistance, and from the viewpoint of varnish processing, pot life is short. long duration and rapid photocurability. The present inventors focused on the fact that allylic unsaturated groups are stable against heat and that the cured product has excellent heat resistance and electrical properties, and created a photocurable insulating varnish incorporating allylic unsaturated groups. The company was currently actively considering the development of .

Generally, allylic unsaturated groups involve degenerative chain transfer;
Because conventional compounds such as diallyl phthalate and triallyl trimellitate easily form a cyclized structure, it is difficult to immediately create a three-dimensional hardened structure with good properties from a liquid monomer without going through the form of a prepolymer. is known to be difficult. The present inventors have conducted research to overcome such limitations and develop a good photocurable insulating varnish. As a result, the present inventors have found that by introducing an allyl group in the form of a urethane bond as described below, It has been found that this object can be suitably achieved. That is, the present invention relates to the general formula:
Represents 0 to 300.

) and a compound (B) having one or more polymerizable unsaturated groups in the molecule, wherein the (A) component is 40 to 100% by weight and (B) This invention relates to a photocurable insulating varnish consisting of 60 to 0% by weight of components and a sensitizer added thereto. More specifically, R in the above formula of the present invention is a diisocyanate compound, such as hexamethylene diisocyanate, 2,4 (or 2,6)-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 4
・4'-diphene: Nil diisocyanate, 3,3'-
Dimethyl-4,4'-diphenyl diisocyanate, 3
・3'-dimethyl-4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 3
・Residues of one type or a mixture of several types such as 3'-dimethoxy-4,4'-diisocyanate and 2-chloro-1,4-phenyl diisocyanate may be mentioned, but are limited to these. Rather, R in the formula may include an ether bond, ester bond, urethane bond, amide bond, imide bond, etc., but the average molecular weight of R is preferably in the range of 50 to 300. used.

If the average molecular weight of R is greater than 300, problems such as high melting point, high viscosity, and decreased compatibility with other compounds having photocopolymerizable unsaturated groups may occur, which is undesirable. The crosslinking density also decreases, and there is a high possibility that the properties of the cured product will deteriorate. Further, those having an average molecular weight of less than 50 are often unstable as compounds and are not preferred. For this reason, the average molecular weight of R is particularly preferably in the range of 60 to 250. The diallyl compound represented by the general formula (A) is produced from 2 moles of allyl alcohol and 1 mole of diisocyanate compound without any catalyst, or in some cases with a small amount of catalyst, such as a Lewis base, especially tertiary amines, phosphines, or This is achieved by carrying out a conventional urethanization reaction using an organometallic compound of a Lewis acid. Among the diallyl compounds obtained in this way, those with a low melting point are mixed with a small amount (0.05 to 5%) of a sensitizer, heated at room temperature or slightly (below 100°C), and irradiated with light for 1 to 20 minutes. In particular, a hardened insulating structure with excellent thermal stability can be obtained. In this case, the sensitizer may be an ordinary photopolymerization initiator, such as benzoin or benzoin methyl ether, or may be used in combination with α・α7-azobisisobutyronitrile, benzoyl peroxide, etc. Good too. Furthermore, the light source used in this case is one that efficiently generates ultraviolet rays, such as a high-pressure mercury lamp or an ultra-high-pressure mercury lamp. When the diallyl compound (A) produced as described above has a high viscosity or is in a solid state, the above compound may be used for the purpose of lowering the viscosity and adjusting the properties of the cured product. It is better to mix (A) with another photocopolymerizable compound (B) having one or more unsaturated groups in the molecule. The photocopolymerizable compound (B) includes acrylic acid (methacrylic acid) ester, di(tri,tetra)acrylic acid (methacrylic acid) di(tri,tetra)ester, acrylic (methacrylic)amide, acrylonitrile, Examples include vinyl monomers such as styrene and vinyltoluene, and unsaturated polyester resins.

Examples of the unsaturated polyester resins include unsaturated dibasic acids such as maleic acid, maleic anhydride, and fumaric acid, succinic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, isophthalic acid, terephthalic acid, and anhydrides of these acids. An esterification reaction product of a saturated dibasic acid such as a dibasic acid or a lower alkyl ester and a glycol such as ethylene glycol, diethylene glycol, or propylene glycol is used. In this case, the blending ratio of the chemical composition (A) made of diallylurethane and the photocopolymerizable unsaturated compound (B) is such that the (A) component is 4
0 to 100% by weight, and component (B) preferably 60-0% by weight.

The reason for this is that if the content of component (A) is less than 40% by weight, the effect of introducing allyl groups, that is, the pot life of the varnish, the electrical properties of the cured product, the heat resistance, etc. will be reduced. The thus obtained varnish composition was heated for 30 seconds to 1 hour in the same manner as above.
An excellent hardened insulating structure can be obtained by irradiating with light for 0 minutes. The present invention is an insulating varnish whose molecules are designed to maximize the advantages of introducing a photocuring method for curing the insulating varnish, and its industrial value is extremely high. EXAMPLES The present invention will be specifically explained in more detail with reference to Examples below.

Example 1 Allylalco! to 1 mole of hexamethylene diisocyanate! Add 2 moles of diaryl urethane and keep at 100℃ for 2 hours to obtain 1 mole of diallyl urethane compound (white solid, melting point 62℃)
.

A varnish was obtained by adding 2% by weight of benzoin methyl ether to this. Sample 1 is a cured product obtained by irradiating this varnish with light for 10 minutes using a high-pressure mercury lamp on a 70° C. hot plate. Example 2 To 59 parts by weight of the diallylurethane compound obtained in Example 1, 40 parts by weight of tetraethylene glycol diacrylate and 1 part by weight of benzoin methyl ether were added to obtain a varnish.

Sample 2 is a cured product obtained by irradiating this varnish with light for 3 minutes using a high-pressure mercury lamp at room temperature. Example 3 49 parts by weight of the diallyl urethane compound obtained in Example 1 were added with an unsaturated polyester resin (resin components: 1.0 mol of propylene glycol, 0.4 mol of succinic acid, and 0.4 mol of fumaric acid).
6 mol), 10 parts by weight of styrene and 1 part by weight of benzoin methyl ether were added to obtain a varnish.

Sample 3 is a cured product obtained by irradiating this varnish with light for 5 minutes using a high-pressure mercury lamp at room temperature. Example 4 2 moles of allyl alcohol are added to 1 mole of 4,4'-diphenylmethane diisocyanate, and 1 mole of diallylurethane as a yellow-white solid or viscous liquid is obtained in the same manner as in Example 1.

A varnish was obtained by adding benzoin methyl ether to this. Sample 4 is a cured product obtained by irradiating this varnish with light in the same manner as in Example 1. Example 5 To 59 parts by weight of the diallyl urethane compound obtained in Example 4,
A varnish was obtained by blending monomers in the same manner as in Example 2.

Sample 5 is a cured product obtained by irradiating this varnish with light in the same manner as in Example 2. Example 6 2 moles of 2,4-toluene diisocyanate were added to 1 mole of bis-(β-hydroxyethyl) terephthalate, kept at 150°C for 2 hours, and then 1 mole of 2,4-toluene diisocyanate and 4 moles of allyl alcohol were added. plus 100-150
Keep at ℃ for 2 hours.

A varnish was obtained by adding 40 parts by weight of the unsaturated polyester resin used in Example 3, 10 parts by weight of styrene, and 2 parts by weight of benzoin methyl ether to 48 parts by weight of the component consisting of the diallyl urethane compound thus obtained. Sample 6 is a cured product obtained by irradiating this varnish with light for 5 minutes using a high-pressure mercury lamp on a hot plate at 40°C. Reference Example 1 99 parts by weight of tetraethylene glycol diacrylate used in Example 2 was added to 1 part by weight of benzoin methyl ether.
A cured product obtained by adding parts by weight and irradiating with light in the same manner as in Example 2 is referred to as Reference Sample 1.

Reference Example 2 30 parts by weight of styrene and 1 part by weight of benzoin methyl ether were added to 69 parts by weight of the unsaturated polyester resin used in Example 3.
A cured product obtained by adding parts by weight and irradiating with light in the same manner as in Example 3 is referred to as Reference Sample 2.

The viscosity changes of the unirradiated varnishes of Examples 1 to 6 and Reference Examples 1 to 2 after 10 hours at 100° C. in a dark room were measured. The dielectric loss tangent in the table above was measured using a transformer bridge, and T (glass transition temperature) was determined by measuring dynamic viscoelasticity at a frequency of 11H2.
When arranged in descending order: It was.

This proves that the pot life of the varnish is significantly extended by incorporating the diallyl urethane compound. The following table shows the results of physical property measurements for Samples 1 to 6 and Reference Samples 1 to 2.
was determined by measuring dynamic viscoelasticity at a frequency of 11H2.

As is clear from the above table, the photocured insulating varnish of the present invention exhibits excellent electrical properties, heat softening resistance, etc., and its practical value is extremely large.

Claims (1)

[Claims] 1 General formula: CH_2=CHCH_2OOCHN-R-NHCOOC
H_2CH-CH_2 (R in the formula consists of an aliphatic, alicyclic or aromatic hydrocarbon group or a derivative residue thereof,
R has an average molecular weight of 50 to 300); and a vinyl monomer or unsaturated polyester resin compound (B) having one or more polymerizable unsaturated groups in the molecule. Component (A) is a mixture of 4
A photocurable insulating varnish comprising 0 to 100% by weight of component (B) and 60 to 0% by weight of component (B), to which a sensitizer is added.